Telephony.



s. G. BROWN:

TELEPHONY. v Arimunion FILED JULY 6, 1914. 1,1 33,923. Patented Mar. 30,1915.

' v N z SHEETS-SHEET 1.

away s. G. BROWN.

7 TELEPHONY. APPLIUA'FIOH FILED JULY 6, 1914.

Patented Mar. 30, 1915;

2 SHEETS-SHEET 2.

- fivezzfo-r azdlzeg G..Brbwrt m TED STATES PATENT carton.

SIDNEY GEORGE BROWN, LONDON, ENGLAND. W

TELEPHONY.

Specification of Letters Patent. Patnted Mar, 30, 1915.

Application filed m; 6, 1914'. Serial No. 849,261.

T all whom it'may concern."

Be it known that I, SIDNEY Gnoncn BRoWN, a subject of the King of GreatBritain, residing at 4 Great Winchester street, in the city and countyof London, England, have invented certain new and useful Improvements inor Relating to'Telephony, ofc which the following is a specification.

This invention relatesto telephony and has reference to telephone relaysystems of the kind in which the two stations between whichcommunication is establishedare connected by way (of relay apparatus soarranged that when voice currents originating in a transmitter at onestationare sent along the line to the relay apparatus the distantreceiving station is rendered incapable of operating the relay apparatusbut is com nected with the source of magnified voice currents producedin'the said relay 'apparatus. In, the specification of my prior BritishPatent No 9179 of 1912 I have described several arrangements foroperating in this manner. 1 p

- The chief ob ects of the present invention are to improve the systemof working in cer- According to the present invention relay apparatus atthe relay station is associated with a change-over switch adapted to bemoved automatically into one or other position immediately voicecurrents commence to fiow from one or other of the terminal stations,thereby placing the particularstation from which the voice currentsoriginate in permanent connection with the energizing portion of therelay apparatus, andplacing the reinforcing portion of this .ap-

paratus iii-permanent connection with the other station, until varyingcurrents are produced by speaking at the latter stat-ion, whereupon'theelectrical conditions are immediately'reversed. I

The'use of a double-pole change-over ,switch enables the relay apparatusto consist Ma single telephone relay,- thus affording simplification andeconomy of working, and

other reinforcing. circuit.

reducing attention on the ator to a minimum.

In order that the invention may be clearly I understood and readilycarried into effect, I

will now describe the same more, fully with reference to theaccompanying drawings, in

which v Figure 1 represents diagrammatically one arrangement ofapparatus constituting a telephone relay system adapted to operate inaccordance with the invention. Figs. 1 and l are fragmentary diagramsillustrating modifications. Fig.2 is a modification of thesystem shownin Fig. 1, and Figs. 3 and 4 are two further modifications. I'will firstdescribe the relay system as illustrated in Fig. 1. A and B representthe ends of two subscribers lines inductively coupled to the two ends ofthe line sections proper D L between which is inserted the relayapparatus. The relay apparatus compart of the o perprises the relayproper C, with :which, is

associated the double-pole throw-over switch D, the latter beingrepresented by the two arms D D and their associated electromagneticactuating means d Ihe relay 0 may be a telephone relay of any ordinaryconstruction such as art electromagnet operating amicrophone ass own,

its energizing portion, represented by the terminals C forming part ofone or other of two circuits including two contacts 0 c of the doublepole switch D, and its rein-.

forcing portion, represented by the termmals U, forming part of twocircuits including the other two contacts namely 0 0 of the said switch;The circuit connections and the: construction of the-double pole switchD are such that when one of the relay energizing circuits is'completedthrough the switch and through a source of variablecurrents due to voicecurrents transnntted from one subscrlbers hne,,one of the reinforcingcircuits of the relay, is simultaneously completed through the switch Dand through means whereby the relay magnified currents are transmittedto-the' other subscribers line, and similarly with respect to theotherrelay energizing circuit and'the The sources of variable'currents'in the relay energizing circuits conveniently consist, asshown, of windings E F of transformers E F respectively, of which theother windings E F are in the lines leading to the correspondingsubscribers lines;

In the position of the parts shown in Fig. 1-it is assumed that thesubscriber on by which the magnified speaking currents 'from theterminals C of the relay G are transmitted along'the line L to thesubscribers line B. So long as the subscriber on line A- continues 'tospeak these conditions are maintained. ,When however, the subscriber online A stops and the subscriber on line B commences to speak the arms" DD of the double pole switch D are tilted in the opposite direction andthe trans-.

- former winding F then becomes thesource once they have been thrownover electromagnetically of variable currents by which the relay C isenergized while the transformer winding E becomes the means by which themagnified speaking currents from the relay C are transmitted along theline I1 to the subscribers. line A. Y

over-balancing pivoted type so that when by the energizing of theelectromagnets d d they remain permanently in -that position untilthrown over electromagnetically in the reverse direction by theenergizing of-the electromagnets (1 (if.

I The energizing of the two pairs of-e1ectroma'gnets'is due tocurrentgderived from l sources of steady current "thatbecome au linesections immediately the respective subscribers commence to speak. Inconnection tornatically switched across the respective with thesubscribers line A, the source of steady current shown for the line Lcon sists of a battery A connected on the one handby way of aheavyinductance A to the i'line wire and on theother hand by way of a frontstop 9 and a tongue 9 to the return wire. The tongue 9? is normallykeptagainst the front stop-g by'a spring 9 or by gravity, butis moved awayfrom the front stop and toward a back stop '9 when a controllingelectromagnet A? is v energized by a steady curregt'from a'local batteryA. A condenser g" revents spark- ,ingat the stops g, g. The circuit ofthe battery A is completed through a voice closed in the speci cationand; drawings of; my prior.British' Patent No. 9179 of 1912,,

current responsive device A. This 'device may conveniently take the formof a vibration device or jum ing switch such as dis- 7 that is to. say'a-balanced or pivoted arm forming part. of thecircuit' of the battery Aand riding upon a resilient reed. serving armature" to an electromagnetadapte be energized by the voice currents' The actual surfaces at whichthe circuit of the battery A -is thus rapidity interrupted: are

preferably composed shown in the fragmentary Fig. 1

- and the battery for providing a rent in the line is also insertedcorresponding over the'switch arms. T carbon, When voice currents fromthe subscriber s line A are inductively transmitted to the electromagnetof the jumping switch A, the armature of this switch vibrates and thebalanced arm dances upon it, thereby destroying or reducing the steadycurrent normally flowassume the position shown in Fig. '1. The

right hand part of Fig.1 corresponds to the left hand part, the jumpingsiwvitc'h B", heavy inductance Bt, and battery B corre-' sponding to theparts A", A and -A --respectively; similarly the post oflice relay B itstongue and stops. 7 v

a The invention is not, of course confined to,

'80 switch Dis electromagnetically actuated to 4 corresponds to the"electromagnet A*, with The switch arms- D 'D may be of the themeans'above described for enabling the voice currents in the subscriberslineA to be transferred to the transformer E and to effect the automaticthrowing over of the arms of the throw-oven switch. For'example, theinductance A might'be connected-at one end to the battery A and at theother end to the mid point'of. an induction coil 'A connected across theline, the other pole of the battery being connected to: earth, and anappropriate earth connection made at the other end of the line section,as

obviously the nductance A5 represented in this figure might beomitted.

where it is seen that the electromagnet A,

Another modification is shown in Fig.1",

of Fig. 1, and its tongue and stops are dis-- pensed with, and thatone'contact of the umping switch A '1s connected by way vof aninductance A to the mid point-0f an inductance A" connected acrosstheline, and the other contact connected to earth. A corresponding earthconnection is, made at the electromagnets d d (as in Fig. 1),

steady curin this earth 'connect1on,an advantagebeing that the strengthof the current at the contacts of the "switch A is considerablyattenuated and sparking is thereby minimized. In this arrangement (Fig.1?*) ,it'is to be noted that the four electromagnets controlling theswitch arms D- D? and thatwhen either subscriber speaks'the pair ofelectromagnets is .temporarlly eenergized,' thus allowing the remainingpair to predominate and throw Thejumping switches A B ma b 3 arenormally energized seams ated at any point in. the respective linesections, either close up toithe relay. apparatus or close up to thesubscribers line, but/in orderthat they mayrespond promptly and readilyto; voice currents, they are preferably placed close to their respectivesubscribers lines as shown: in Figs. 1, 1 and 1 so as to be actuated bythe voice currents before they suffer appreciable attenuation.

The electromagnet. winding of each jumping switch may be connectedacross the line and return wires of the lineproper as shown in Fig. 1;disturbances in the line, however, such for example as arise frominduction and from. currents from the relay 0' are liable to actuate theswitches,

and I therefore prefer to protect" each switchfrom such disturbances byconstituting its electromagnet winding the bridge or part of the bridgeof a bridge connection as shown in Figs.. 1, 1 and 2, as will now beexplained with reference-to Fig; 1. Re-

ferring for convenience of description to-the left hand. end ofthe-figure, itis seen that theelectromagnet winding terminals of; thejumping switch A s are connected. or bridged acro'ssthe bridge arms A ofa bridge connection. One end of each bridge arm is connected to theline. proper L and the other end is connected to part of the transformerwinding by which the line L is inductively coupled to the subscribersline A. A represents an artificial line which is more or less a copy ofthe sub- 1 scribers line with resistance and induct.- anceat the endsimilar in values to those of the subscribers telephone ,set.Consequently, when voice currents in thesub- 1 scribers line A aretransferred by the trans formerto the line proper L the jumping switch Ais actuated and producesthe resultsalready described, but any currentspassing backward along the line divide at the apex of the bridgeconnection and do 1 not affect the jumping switch; oronly to a slightextent.

From the foregoing description of .Figs.

'1, 1 and 1 the system represented-by Fig.

- .03 respectively operate in a similar manner to that described in.connection with: Fig. 1,

but it: is to be observed that a single source of steady current(battery X) serves. for bothlines'Land L. U

jumping switch B to operate.

double pole switch arms D D have already,

In. the arrangements and methods of connectionhitherto described, theoperator at the relay station is unable to attend to any adjustment thatmay be required in the jumping switches A B and their acces- If desired,however, the arrange-- sories. ment may be modified to render thispossible, as shown for example in Fig. 3, where the jumping switches A,B are shown close up against the transformers E and F respectively atthe relay station. It will be understood that when voice\currentstraverse the line L, the jumping switch A destroys or reduces the steadycurrent from the battery A with the result that the electromagneticdevices controlled by the jumping switch B predominate and the double p0e switch is thrown over into the position shown in'the figure.Consequently the voice' currents operate the relay C, and the rein- Iforced currents are transferred by the transformer F to the line L".Corresponding effects take place. if voice currents traverse the line L.It is however to be observed that the reinforced. voice currentstransferred through, say, the transformer F to the line.L,, cause thebalanced arm of the Since the been thrown over and are of theover-balancing type, the operation of thejumping switch B is of .littleimportance provided this switchis not by chance active for an instantduring which the switch A is quieseent.- If the latter event'took placethe switch A. would causethe switch arms D D 'to rock 'into theiralternative position,

the voice currents inthe line L would then be unable to becomereinforced by the relay. In order to avoid this occurrence severalprecautions may-be adopted. According to' one method the reinforcedvoice currents from the relay C are tapped by means of a transformer, asshown at H in Fig. 3, and the tapped portion of the current is made totraverse two coils A, Bf", which are associated with the jumpingswitches'A B respectively in such a way as. to. cause-their pivoted orbalanced arms to dance and thereby insurethat both switches are'kept inan active-condition so long as voice 'currents are passing through andbeing reinforced by the relay. This. arrangement may in some casespresent a defect in that, whereas the coilsA"".-B"* are traversed by thesame current, the energizing winding of the jumping switch A istraversed by attenuated voice currents, when the energizing winding ofthe jumping. switch B is traversed by the relay augmented voice cur;

rents, and similarl'y' the switch B is traversed by attenuated currentswhen A? is traversed by augmented voice currents, the

result bein that ,the two jumping switches lbs are not an jectto exactlythe same conditions. A.preferable arrangement, therefore,

is to so arrange the coils A B that they oppose the action of therespective energizing windings of the jumping switches. If, then, theelectrical characteristics of the circuit of the coils A B are madeequal to those of the lines L and L, as can be done by introducing anartificial line J of appropriate electrical value in the circuit of-thecoils A" B, the currents in the coil B will neutralize or oppose thecurrents in the energizing winding of the switch B when the reinforcedvoice currents are being transferred to the line L", whereas the similarcurrents in the coil A will predominate over the attenuatedcurrents inthe energiz-v ing winding of the switch A, thus insuring that the switchis kept quiescent and the switch A is kept active so'long as voicecurrents are traversing. the line L. Similarly when, voice currents aretraversing the line L", the switch B is kept active andthe switch A iskept quiescent. In the arrangement just described, the, coupling ofthecoil A with the energizing winding of the ,switch A, and the coupling ofthe coil B with the'energizing windingofthe coil B,

- must not be very close, slnce otherwise .coils ddi, (1 (1, aresupplied with current I ters Patent. of the United States is:-

' 1. In a telephone relay system betweenenergy might be transferred backinto the lines L or LP. Instead of having to avoid the too closecoupling above referred to, a

modified system may be adopted as shown in I 'Fig. 4;. In thisarrangement, the relay augmented current tapped'by way of thetransformer H is made to: operate a jumping switch C which controls thecircuit of a battery 0* by means of which the energizing by way of thejumping switches A B". So

long as the relay is operating to reinforce" voice currents arrivingfrom either direction, say from the line L, as represented by thedrawing, the jumping switch C 'is active and the steady current thatmight otherwise flow from the battery 0" inthe coils 11 is destroyed orreduced, so that in the event of a momentary quiescence of the j pingswitch B the arms of th double pole switch are not thrown over. b

What I claim a'nd desire to secureby Lettwo terminal stations, thecombination with relay apparatus, relay energizing circuitsthrough-which voice currents from the terminal stations may pass, andrela circuits through which the relay magnifi currents may pass, ofswitching means normally assuming and maintaining either of twopositions in one of which the rela V energizing circuit corresponding toone sta ion'is closed and receiving conditions for the distant stationare-established, while in theother posi tion therelay energizing circuitfor the ment oned station is closed'and recelving' conditions for thefirst mentioned station are established, and means whereby the voicethrough which the relaymagnified currents [may pass, of a double-poleoverbalancing change-over switch normally assuming and maintainingeither of two positions in one of relay energizing circuits which, therelay energizing circuit corre-' spondingto one station is closed andreceivmg conditlons for the distant station are established, while inthe other positionthe relay energizing circuit for the last men-..

tioned station is closed and receiving conditions for the firstmentioned station are.

established, and means whereby the voice currents from either terminalstation automatlcally cause the change-over switch to assume theposition in which the distant station can receive the relay magnifiedcurrents, if said switch is not already in that position. 3. In atelephone relay system between two terminalstations, the combinationwith I relay apparatus, "relay energizing circuits through which voicecurrents from the terminal stations may pass, and relay circuits throughwhich the relay magnified currents may pass, of a double-poleoverbalancing changeover switch normally assuming and maintaining eitherof two positions in one of whlch, the relay energizing circuitcorresponding ceiving conditions for the distant station are to onestation is closed and reestablished, while in the other. position itcloses the relay energizingcircuit for the last mentioned stationisclosed and receiving conditions tion are established, electromagneticdevices for moving the double-pole. change-over switchinte eitherposition, and means whereby voice' currents from either one stationcause the-activity of the respectiveelectroma switch into the operative.of the voice currents to the other station.

--4. In a telephone relay system between two termmal stations, thecombination with relay apparatus, relay,

energizin' circuits through which voice g currents from the ter- -minalstations may.pa"ss,'and' rela circuits through which the relay magnifiecurrents may pass, of a double-pole over-balancing change-over switchnormally assuming and mainta' either of two positionsin one of which, te relay energizing circuit correfor the first-mentioned staetic devicethat moves the change-over position for bring- Y mg about magnificationand transmission sponding to one station is closed and receivingconditions .for the distant station are established, while in theiotherposition it closes the relay energizing circuit forfthe last mentionedstation is closed and receiv-- ing conditions for the, first mentionedstation are es tablished, electromagnetic devices rents whereby onspeaking at either station the corresponding electromagnetic meanscomplete the energizing circuit of the corresponding electromagneticdevice and thereby correspondingly actuate the changeover switch.

-5. In a telephone relay system between two terminal stations, thecombination with relay apparatus, Ire-lay energizing circuits throughwhich voice currents from the terminalstations may pass, andrelay-circuits through Whichi therel-ay magnified currents may pass, ofa double-pole overbalancing change-over switch, which in one positionvcloses the relay energizing circuit corresponding to one station andestablishes 're- 'ceiving conditions for the distantstations,

While in the other positionjt closes the relay energizing circuit forthe last mentioned stationand establishes receiving conditions for thefirst mentioned station, electromagnetic devices for moving thedouble-pole change-over switch into either position, electromagneticmeans forcontrolling the energizing circuits of the said electromagneticdevices, a bridge connection in the line wire between each station andthe relay apparatus, and an electrpmagnetic device re s onsive to voicecurrents included inthe ridge of each bridge connection for operatingsaid electromagnetic means, substantially as and for the purposespecified.

t 6. In. a telephone relay system between w a s' gle relay comniontoboth stations, of a double-pole change-over switchwhich in one 7position closes the relay energizing circuit corresponding to onestation and establishes receiving conditions for the distant station,"wh11e 1n the other position it closes the relay,

energizing circuit for the last mentioned station and establishesreceiving conditions for the first mentioned station, and transformerswhereby voice currents from the line-proper of each station aretransferred to the corresponding +relay energizing circuit orthe re- 4electromagnets electrically connected in the .line proper, means forsending a steady'curv lay magnified voice currents are transferred to theproper according tothe direction of speech transmission, switchactuating terminal stations, the combination with rent through the lineto energize the electromagnets, electromagnetic devices for renderingthe aforesaid means operative, and devices responsive to voice currentswhereb on speaking at either station the correspon ing switch actuatingelectromagnts become active. o,

' 7. In a telephone relay system between two terminalstations, thecombination with relay apparatus, relay energizing circuits throughwhich voice currents from the terminal stations may pass, and relaycircuits through which the. relay magnified currents may pass, ofachange-over switch which in one position closes the relay energizingcircuit corrresponding to one'station' and establishes receivingconditions for the distant station, while'in the other position itcloses the relay energizingcircnit for the last men-- tioned station;and establishesreceiving conditions for the first mentioned station,electromagnets'electrically connected in the line proper from eachterminal station, means whereby'the electromagnets become energized,electromagnetic device's responsive to voice-currents whereby onspeaking-at either station the circuit-closing means of theelectromagnets become operative in closing theirenergizing circuits andthereby bring about actuation of the change-over switch, andmeanswhereby the efi'ect ofthe relay-augmented voice currents on thevoice-currentresponsive device that is associated with the section ofthe line to which such currents are being transmitted is neutralized orcoun eracted for so long as the relay apparatus continues to operate forthe directionin question.

8. In 'a telephone relay system between two terminal stations, thecombination with a single relay common to both stations, of adouble-pole: change-over switch which in one positiontcloses the relayenergizing circuit corresponding to one station and establishesreceiving conditions for thedistant station", while in the otherposition it closes the relay energizing circuit for the last mentionedstation and establishes receiving conditions for the first mentionedstation,electromagnets associated with-the switch; and electricallyconnected to the line proper from each terminal station, abatteryconnectedto sendi adivided steady current along the line toenergize the electromagnets,battery circuit closing means, andelectromagntic devices res onsive" td voice-currents whereby on sperm'ng at either station the battery circuit closing means close thebattery circuit.

,Jn testimony whereof I aflix my signature" in presence of twowitnesses.

a SIDNEY GE ORGE BROWN.-T

Witnesses:

T. Samar Wannm, E. C. WALKER;

